GNS561, a clinical-stage PPT1 inhibitor, is efficient against hepatocellular carcinoma via modulation of lysosomal functions.

Hepatocellular carcinoma is the most frequent primary liver cancer. Macroautophagy/autophagy inhibitors have been extensively studied in cancer but, to date, none has reached efficacy in clinical trials. In this study, we demonstrated that GNS561, a new autophagy inhibitor, whose anticancer activity was previously linked to lysosomal cell death, displayed high liver tropism and potent antitumor activity against a panel of human cancer cell lines and in two hepatocellular carcinoma in vivo models. We showed that due to its lysosomotropic properties, GNS561 could reach and specifically inhibited its enzyme target, PPT1 (palmitoyl-protein thioesterase 1), resulting in lysosomal unbound Zn2+ accumulation, impairment of cathepsin activity, blockage of autophagic flux, altered location of MTOR (mechanistic target of rapamycin kinase), lysosomal membrane permeabilization, caspase activation and cell death. Accordingly, GNS561, for which a global phase 1b clinical trial in liver cancers was just successfully achieved, represents a promising new drug candidate and a hopeful therapeutic strategy in cancer treatment.Abbreviations: ANXA5:annexin A5; ATCC: American type culture collection; BafA1: bafilomycin A1; BSA: bovine serum albumin; CASP3: caspase 3; CASP7: caspase 7; CASP8: caspase 8; CCND1: cyclin D1; CTSB: cathepsin B; CTSD: cathepsin D; CTSL: cathepsin L; CQ: chloroquine; iCCA: intrahepatic cholangiocarcinoma; DEN: diethylnitrosamine; DMEM: Dulbelcco's modified Eagle medium; FBS: fetal bovine serum; FITC: fluorescein isothiocyanate; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; HCC: hepatocellular carcinoma; HCQ: hydroxychloroquine; HDSF: hexadecylsulfonylfluoride; IC50: mean half-maximal inhibitory concentration; LAMP: lysosomal associated membrane protein; LC3-II: phosphatidylethanolamine-conjugated form of MAP1LC3; LMP: lysosomal membrane permeabilization; MALDI: matrix assisted laser desorption ionization; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MKI67: marker of proliferation Ki-67; MTOR: mechanistic target of rapamycin kinase; MRI: magnetic resonance imaging; NH4Cl: ammonium chloride; NtBuHA: N-tert-butylhydroxylamine; PARP: poly(ADP-ribose) polymerase; PBS: phosphate-buffered saline; PPT1: palmitoyl-protein thioesterase 1; SD: standard deviation; SEM: standard error mean; vs, versus; Zn2+: zinc ion; Z-Phe: Z-Phe-Tyt(tBu)-diazomethylketone; Z-VAD-FMK: carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]- fluoromethylketone.

GNS561 acts as a potent anti-fibrotic and pro-fibrolytic agent in liver fibrosis through TGF-ß1 inhibition.

BACKGROUND: Hepatic fibrosis is the result of chronic liver injury that can progress to cirrhosis and lead to liver failure. Nevertheless, there are no anti-fibrotic drugs licensed for human use. Here, we investigated the anti-fibrotic activity of GNS561, a new lysosomotropic molecule with high liver tropism. METHODS: The anti-fibrotic effect of GNS561 was determined in vitro using LX-2 hepatic stellate cells (HSCs) and primary human HSCs by studying cell viability, activity of caspases 3/7, autophagic flux, cathepsin maturation and activity, HSC activation and transforming growth factor-ß1 (TGF-ß1) maturation and signaling. The contribution of GNS561 lysosomotropism to its anti-fibrotic activity was assessed by increasing lysosomal pH. The potency of GNS561 on fibrosis was evaluated in vivo in a rat model of diethylnitrosamine-induced liver fibrosis. RESULTS: GNS561 significantly decreased cell viability and promoted apoptosis. Disrupting the lysosomal pH gradient impaired its pharmacological effects, suggesting that GNS561 lysosomotropism mediated cell death. GNS561 impaired cathepsin activity, leading to defective TGF-ß1 maturation and autophagic processes. Moreover, GNS561 decreased HSC activation and extracellular matrix deposition by downregulating TGF-ß1/Smad and mitogen-activated proteine kinase signaling and inducing fibrolysis. Finally, oral administration of GNS561 (15 mg/kg per day) was well tolerated and attenuated diethylnitrosamine-induced liver fibrosis in this rat model (decrease of collagen deposition and of pro-fibrotic markers and increase of fibrolysis). CONCLUSION: GNS561 is a new potent lysosomotropic compound that could represent a valid medicinal option for hepatic fibrosis treatment through both its anti-fibrotic and its pro-fibrolytic effects. In addition, this study provides a rationale for targeting lysosomes as a promising therapeutic strategy in liver fibrosis.

GNS561, a new lysosomotropic small molecule, for the treatment of intrahepatic cholangiocarcinoma.

Among the acquired modifications in cancer cells, changes in lysosomal phenotype and functions are well described, making lysosomes a potential target for novel therapies. Some weak base lipophilic drugs have a particular affinity towards lysosomes, taking benefits from lysosomal trapping to exert anticancer activity. Here, we have developed a new lysosomotropic small molecule, GNS561, and assessed its activity in multiple in vitro intrahepatic cholangiocarcinoma models (HuCCT1 and RBE cell lines and patient-derived cells) and in a chicken chorioallantoic membrane xenograft model. GNS561 significantly reduced cell viability in two intrahepatic cholangiocarcinoma cell lines (IC50 of 1.5 ± 0.2 µM in HuCCT1 and IC50 of 1.7 ± 0.1 µM in RBE cells) and induced apoptosis as measured by caspases activation. We confirmed that GNS561-mediated cell death was related to its lysosomotropic properties. GNS561 induced lysosomal dysregulation as proven by inhibition of late-stage autophagy and induction of a dose-dependent build-up of enlarged lysosomes. In patient-derived cells, GNS561 was more potent than cisplatin and gemcitabine in 2/5 and 1/5 of the patient-derived cells models, respectively. Moreover, in these models, GNS561 was potent in models with low sensitivity to gemcitabine. GNS561 was also efficient in vivo against a human intrahepatic cholangiocarcinoma cell line in a chicken chorioallantoic membrane xenograft model, with a good tolerance at doses high enough to induce an antitumor effect in this model. In summary, GNS561 is a new lysosomotropic agent, with an anticancer activity against intrahepatic cholangiocarcinoma. Further investigations are currently ongoing to fully elucidate its mechanism of action.

Early deficits in glycolysis are specific to striatal neurons from a rat model of huntington disease.

In Huntington disease (HD), there is increasing evidence for a link between mutant huntingtin expression, mitochondrial dysfunction, energetic deficits and neurodegeneration but the precise nature, causes and order of these events remain to be determined. In this work, our objective was to evaluate mitochondrial respiratory function in intact, non-permeabilized, neurons derived from a transgenic rat model for HD compared to their wild type littermates by measuring oxygen consumption rates and extracellular acidification rates. Although HD striatal neurons had similar respiratory capacity as those from their wild-type littermates when they were incubated in rich medium containing a supra-physiological glucose concentration (25 mM), pyruvate and amino acids, respiratory defects emerged when cells were incubated in media containing only a physiological cerebral level of glucose (2.5 mM). According to the concept that glucose is not the sole substrate used by the brain for neuronal energy production, we provide evidence that primary neurons can use lactate as well as pyruvate to fuel the mitochondrial respiratory chain. In contrast to glucose, we found no major deficits in HD striatal neurons' capacity to use pyruvate as a respiratory substrate compared to wild type littermates. Additionally, we used extracellular acidification rates to confirm a reduction in anaerobic glycolysis in the same cells. Interestingly, the metabolic disturbances observed in striatal neurons were not seen in primary cortical neurons, a brain region affected in later stages of HD. In conclusion, our results argue for a dysfunction in glycolysis, which might precede any defects in the respiratory chain itself, and these are early events in the onset of disease.